Compact microbeam radiation therapy systems and methods for cancer treatment and research

ABSTRACT

The present subject matter relates to compact, non-synchrotron microbeam radiation therapy (MRT) systems and methods for cancer research and treatment based on a carbon nanotube distributed x-ray source array technology. The systems and methods can deliver microscopically discrete x-ray radiation at peak dose rate of 10 Gy per second or higher. The x-ray radiation can be provided by a spatially distributed x-ray source array. The technology can be used, for example and without limitation, for human cancer treatment, for intra-operative radiation therapy, and for pre-clinical cancer research on animal cancer models.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 12/688,425 filed Jan. 15, 2010, which claims thebenefit of and priority to U.S. Provisional Application No. 61/205,240,filed Jan. 16, 2009, the entire disclosures of which are hereinincorporated by reference.

GOVERNMENT INTEREST

This invention was made with government support under Grant Nos. U54 CA119343 and 1R21 CA 118351-01 awarded by the National Cancer Institute.The government has certain rights in the invention.

TECHNICAL FIELD

The subject matter disclosed herein relates generally to radiotherapysystems and methods. More particularly, the subject matter disclosedherein relates to microbeam radiotherapy systems and methods for cancertreatment and research. Microbeam Radiotherapy (MRT) radiation can becharacterized by its microscopically discrete spatial radiationdistribution (beam width is less than 1 millimeter and beam separationis several millimeters) and ultra-high dose rate (10 Gy/s or higher).

BACKGROUND

The fundamental challenge of radiotherapy is to treat cancer patientseffectively and safely. Current radiotherapy systems and methods provideexcellent benefits for patients with early stage and radiosensitivecancers, but these benefits diminish for patients with radioresistanttumors (e.g., brain or pancreas cancers) and patients with late stagetumors. For these patients, the radiation needed to eradicate the tumorcan cause intolerable or fatal radiation damage. This is especially thecase for pediatric patients, whose rapidly developing normal tissues areoften more radiosensitive than their tumors, and who therefore cannottolerate radiotherapy that would be curative for adults with the samedisease. As a result, normal tissue collateral damage is a majorlimitation in current radiotherapy, preventing effective radiotherapytreatments for cancer patients of a young age, patients with centralnerve system cancers, radioresistant cancers, and late stage cancer withlarge tumors. These cancer patients currently have a poor prognosis.

Microbeam Radiotherapy (MRT) is a unique form of radiation that hasshown an extraordinary ability to eradicate tumors while sparing normaltissue in numerous animal studies. MRT utilizes multiple narrow but wellseparated x-ray planar beams (i.e., “microbeams”) and delivers radiationat extremely high dose rate. MRT radiation differs from conventionalradiotherapy radiations in two aspects: dose spatial discreteness anddose temporal rate. In conventional therapy, the dose rate is about 100times lower and the dose distribution is microscopically continuous inspace. The current solution, which is not always effective, is to usemultiple treatments at 2 Gy per treatment. In contrast, animal studieshave shown that single treatments at a dose level of several hundred Gy(e.g., about 10² Gy or greater) can eradicate a tumor while sparingnormal tissue, including developing tissue in the central nervoussystem.

There are currently two hypotheses for the mechanism by which MRT canprovide tumor eradication while sparing normal tissue. First, it isbelieved that tumor microvasculature does not repair itself well whilenormal tissue does. Second, there appears to be a bystander effectwherein unirradiated tumor cells die with irradiated tumor cells throughcell-cell signaling (See, e.g., D. Slatkin et al., Proc. Natl. Acac.Sci. USA, Vol 92, pp 8783-8787, 1995). However, the underlying mechanismof MRT is still poorly understood. Nonetheless, MRT is extremelyattractive for human application as the key challenge of radiotherapyhas been how to eradicate tumors with minimal collateral damage to thehost normal tissue.

Unfortunately, however, MRT requires that x-rays with an extremely highdose rate (e.g., on the order of 100 Gy/s or higher) are needed toirradiate tissues in a fraction of a second to assure minimal broadeningof the micro slices due to movement of the target. This dose rate isseveral orders of magnitude higher than what is typically used forconventional radiation therapy.

Existing x-ray tube technologies today cannot provide a MRT dosedistribution and dose rate as the MRT dose rate can be thousands oftimes that of state-of-art radiotherapy machines (˜5 Gy/min). The highdose rate is thought to be important for minimizing the broadening (dueto the object motion) of the tens of micron wide microbeam requiredduring irradiation of live objects. A conventional x-ray tube comprisesa metal filament (cathode) which emits electrons when it is resistivelyheated to over 1000° C. and a metal target (anode) that emits x-ray whenbombarded by the accelerated electrons. The spatial resolution of anx-ray source is determined by the size of the focal spot which is thearea on the x-ray anode that receives the electron beam. Because of thehigh operating temperature and power consumption, essentially allcurrent commercial x-ray tubes are single-pixel devices where x-rayradiations are emitted from single focal spots on the anodes. The heatload of the anode limits the maximum x-ray flux of an x-ray tube. Togenerate the small MRT beam size at the ultrahigh dose rate using thecurrent x-ray technology would require an ultrahigh electron beamdensity and heat load that are beyond physical possibility. Forinstance, the state-of-art high-power x-ray tube operating at ˜100 kWdelivers only about 1-10 cGy/s at patient with ˜0.6 m source-objectdistance

As a result, due to this high required dose rate, MRT has thus far beenstudied exclusively using synchrotron radiation, for instance at theNational Synchrotron Light Source (NSLS) in the United States and at theEuropean Synchrotron Radiation Facility (ESRF) in Grenoble, France.Therefore, in order to speed up the research that may advance thepromising cancer treatment for potential human application, there is aneed for compact, non-synchrotron source MRT systems and associatedmethods that can be widely available for cancer centers for preclinicalresearch and clinical application.

SUMMARY

In accordance with this disclosure, compact, non-synchrotron source MRTsystems and methods for microbeam radiotherapy are provided. In oneaspect, a method for microbeam radiation therapy is provided. The methodcan comprise positioning a distributed x-ray source array about a targetto be irradiated, the x-ray source array comprising a plurality ofcarbon-nanotube field emission x-ray sources, and simultaneouslygenerating a plurality of x-ray microbeams from the plurality ofcarbon-nanotube field emission x-ray sources.

In another aspect, a microbeam radiotherapy system is provided. Thesystem can comprise a distributed x-ray source array comprising aplurality of carbon-nanotube field emission x-ray sources, each of thex-ray sources being positioned to direct x-rays towards a common focus,a microbeam array collimation, a positioning device for aligning atarget with the plurality of x-ray microbeams, and a control system incommunication with each of the plurality of x-ray sources in thedistributed x-ray source array for simultaneous generation of aplurality of x-ray microbeams from the plurality of x-ray sources.

Although some of the aspects of the subject matter disclosed herein havebeen stated hereinabove, and which are achieved in whole or in part bythe presently disclosed subject matter, other aspects will becomeevident as the description proceeds when taken in connection with theaccompanying drawings as best described hereinbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present subject matter will be morereadily understood from the following detailed description which shouldbe read in conjunction with the accompanying drawings that are givenmerely by way of explanatory and non-limiting example, and in which:

FIG. 1A is a side view of microbeam radiotherapy of a target within anobject;

FIG. 1B is a graphical representation of the dose rate distributionacross the x-ray microbeam of FIG. 1A;

FIG. 2 is an image of a horizontal histological section of the hindbrainof a rat irradiated using a method for microbeam radiotherapy;

FIG. 3 is a schematic diagram of a field emission x-ray source for usewith a microbeam radiotherapy system according to an embodiment of thepresently disclosed subject matter;

FIG. 4 is a schematic diagram of a field emission x-ray source for usewith a microbeam radiotherapy system according to another embodiment ofthe presently disclosed subject matter;

FIG. 5 is a top plan view of a microbeam radiotherapy system accordingto an embodiment of the presently disclosed subject matter;

FIG. 6 is a top plan view of a microbeam radiotherapy system arranged ina ring-shaped array according to an embodiment of the presentlydisclosed subject matter;

FIG. 7 is a top plan view of a microbeam radiotherapy system arranged ina polygonal array according to an embodiment of the presently disclosedsubject matter;

FIG. 8 is a side view of microbeam radiotherapy of a target within anobject according to an embodiment of the presently disclosed subjectmatter; and

FIG. 9 is a flow chart for a method for microbeam radiotherapy accordingto an embodiment of the presently disclosed subject matter.

DETAILED DESCRIPTION

A traditional x-ray source generates x-ray radiation from a small areaon the x-ray anode (“focal spot”) that receives electrons. The localtemperature on the anode can reach over 1500° C. when it is bombarded bythe high energy electrons. The maximum x-ray dose can be limited by theheat load that can be tolerated by the anode, which is also related tothe size of the focal spot. For instance, a clinical linear accelerator(LINAC) can deliver a dose of only about 5 Gy/min. In contrast, thepresent subject matter provides compact, non-synchrotron source MRTdevices, systems, and methods that can utilize multiple separated,narrow x-ray planar or line beams to deliver radiation at acomparatively higher dose rate. The MRT devices, systems, and methodscan be used, for example, for cancer treatment for humans includingbrain tumors and for intra-operative radiation therapy. It is alsoenvisioned that MRT devices, systems, and methods as disclosed hereincan be used for cancer research in animal models.

As discussed above, MRT differs from conventional radiotherapytechniques in both dose spatial discreteness and dose temporal rate.Specifically, referring to FIGS. 1A and 1 B, rather than a single, broadbeam that provides a substantially continuous dose distribution acrossthe beam width, devices, systems, and methods for MRT produce aplurality of x-ray microbeams MB each having a beam width on the orderof about 1 mm or smaller. As can be seen in FIG. 2, a sample irradiatedusing an MRT method can be identified by a plurality of distinct x-raybeam paths. The plurality of microbeams MB can be directed toward atarget T (e.g., a tumor), which can be contained within an object O.

A second feature that differentiates MRT from conventional radiotherapyis the comparatively high temporal dose rate. Previously disclosedsystems and methods for MRT produce x-ray using a high energysynchrotron or a conventional X-ray tube source, but each of theseoptions has significant drawbacks as discussed above. In contrast, thepresently-disclosed subject matter provides that comparatively hightemporal dose rates sufficient for MRT can be achieved using a spatiallydistributed x-ray source array composed of a plurality of individualx-ray sources that can be positioned about object O.

In one aspect of the presently disclosed subject matter, the spatiallydistributed x-ray source array can be based on a carbon nanotube (CNT)distributed x-ray source array technology. For example, CNT fieldemitters are disclosed in U.S. Pat. No. 6,876,724, titled “Large-AreaIndividually Addressable Multi-Beam X-Ray System and Method of FormingSame”; U.S. Pat. No. 6,850,595, titled “X-Ray Generating Mechanism UsingElectron Field Emission Cathode”; and U.S. Pat. No. 6,553,096, titled“X-Ray Generating Mechanism Using Electron Field Emission Cathode”, thedisclosures of which are incorporated by reference herein in theirentireties.

Exemplary configurations for a field emission x-ray source areillustrated in FIGS. 3 and 4. In the exemplary configurations shown, afield emission x-ray source 100 can comprise a field emission cathodestructure 110, such as, for example, a nanostructure or carbon nanotubefilm on a conducting substrate. A gate electrode 120 (e.g., a highmelting temperature metal grid) can be positioned above cathode 110 suchthat applying a voltage between cathode 110 and gate electrode 120 cancause electrons to be field emitted from cathode 110, for example as anelectron beam EB, and directed towards an anode 130 for generation of anx-ray beam. X-ray source 100 can further comprise a focusing electrode140 for focusing electron beam EB before it reaches anode 130, therebyreducing the size of the focal spot on anode 130.

The system can further comprise a microbeam collimator 150, shown inFIG. 3, which can be positioned in the path of the emitted x-ray beam toallow only selected x-ray microbeams MB having a defined beam thicknessd to be transmitted, thereby defining the irradiation area. In oneembodiment shown in FIG. 5, for example, collimator 150 can producefan-beam x-ray radiation with a narrow beam width (e.g., having a beamwidth of between about 0.01 mm and 1 mm). As a result, a thin-slice oftarget T can be irradiated by x-ray microbeams MB. To minimize thedamage to the normal tissues, the fan-beam angle θ (i.e., the spread ofthe fan-beam) can also be collimated such that the x-ray radiationcovers primarily the region occupied by target T. In addition, thesystem can also comprise a radiochromic film (e.g., Gafchromic XR-QA)positioned between each x-ray source 100 and target T. In thisconfiguration, x-ray microbeam MB can be generated with significantlyhigher dose rate than what is used in clinical treatment. In anotherarrangement, the system can comprise a multi-slit microbeam collimatoror a plurality of collimators 150, shown in FIG. 4, which can likewisebe positioned in the path of the emitted x-ray beam. This arrangementcan create a plurality of non-overlapping (e.g., parallel) x-raymicrobeams MB emitted from each of x-ray sources 100.

To achieve the high dose rate required by MRT, a plurality of x-raysources 100 can be assembled in a distributed x-ray source array 200 asshown in FIG. 5. Each x-ray source 100 can be a distinct element, withan independent cathode 110 and anode 130, which can be operatedindependently or in combination with other of the plurality of x-raysources 100. Alternatively, x-ray source array 200 can comprise an anodering and an opposing cathode ring inside a vacuum container. In thisalternative configuration, cathode ring and anode ring can be operatedcollectively to produce x-ray radiation from the anode ring andirradiate target T within object O.

In either arrangement, x-ray source array 200 functions as a distributedx-ray source. Instead of using one parallel x-ray beam delivering theradiation from one direction or two orthogonal beam arrays (i.e., asdone in the experiments performed at the synchrotron sources), x-raysource array 200 surrounds target T to be irradiated. In this way, x-rayradiation can be delivered from multiple directions to a common focus toincrease the amount of radiation received at target T without increasingthe amount of radiation received at any intervening portion of object Ooutside of target T. In addition, each of the plurality of x-ray sources100 can be arranged such that x-ray microbeams MB from one of x-raysources 100 irradiate a first portion of target T, x-ray microbeams MBfrom a second of x-ray sources 100 irradiate a second portion of targetT different from the first portion, and so on. For instance, referringto FIG. 8, a first set of x-ray microbeams MB can irradiate target Talong a plurality of parallel radiation planes while a separate set ofx-ray microbeams, designated MB′ in FIG. 8, can irradiate target T alongradiation planes that are interleaved with the radiation planes of thefirst set of x-ray microbeams MB. In this way, the x-ray radiation attarget T has a substantially continuous dose distribution even thougheach individual x-ray microbeam MB does not.

As a result, by distributing the x-ray power over a large areasurrounding target T, x-ray source array 200 can generate micro-planarx-ray beams with dose rates at target T that are sufficient for MRT. Forexample, x-ray source array 200 can generate dose rates on the order ofabout 0.1 to 100 Gy/sec, or it can generate much higher dose rates onthe order of 500 Gy/sec. Meanwhile, portions of object O outside oftarget T only receive x-ray radiation from a single x-ray microbeam MB(or group of microbeams) rather than the combined radiation at thecommon focus, and thus the dose rate for these intervening portions canbe much lower.

X-ray source array 200 can be configured to be in any of a variety ofgeometries, such as a ring, an arc, a polygon, or a linear array. Forinstance, in one configuration shown in FIG. 6, x-ray source array 200can have a ring-shaped structure. Object 0 can be positioned inside thering structure, with target T at a focus of the plurality of x-raysources 100, and a plurality of x-ray microbeams can thereby be emittedfrom multiple locations along a circumference of the ring towards targetT. In another configuration shown in FIG. 7, x-ray source array 200 canhave a polygonal structure with multiple segments, each segmentessentially operating as a linear x-ray source array. Although thering-shaped array and polygonal array configurations shown in thefigures only have x-ray sources 100 on a portion of x-ray source array200, it should be understood by those having skill in the art that x-raysources 100 can be positioned about the entirety of x-ray source array200 to more fully distribute the emitted x-ray microbeams MB abouttarget T.

Compared to conventional x-ray tubes that typically generate x-rays froma small area on the x-ray anode, therefore, x-ray source array 200distributes the power over a larger area and/or to multiple focal pointson the x-ray anode so that a high dose rate can be achieved. Primarilybecause of the limitations of the heat load of the x-ray anode, acurrent state-of-art commercial thermionic x-ray tube can be operated ataround 100 kW at an effective focal spot size of 1×1 mm (afterreflection). This is insufficient for the dose rate required for MRT.Specifically, previous study of MRT indicates that a dose rate in theorder of 100 Gy/sec can be effective, but achieving such dose rates haspreviously only been possible using a synchrotron source. In the presentsystems and methods, however, x-ray microbeams MB can be generatedaround the circumference of a ring- or polygon-shaped anode structureand directed towards target T. By distributing the power over a largearea, a much higher x-ray dose can be achieved without generatingexcessive heat loads at any one x-ray anode. Further, through the use ofcarbon-nanotube-based field emission x-ray sources 100, the size of thex-ray focal spot can be reduced compared to prior art devices (i.e.,less than 1×1 mm).

Further, a system for microbeam radiotherapy can comprise a controller210 that can set the treatment parameters, including the dose to bedelivered, the dwell time, the width of the x-ray radiation plane, andthe spacing between adjacent radiation planes. In addition, the systemcan also comprise a patient bed for supporting the patient undergoingradiotherapy (i.e., object O) and a positioning device 220 that canalign target T with the radiation field. For instance, the alignment ofx-ray source array 200 can be performed using an x-ray computedtomography (CT) scanner 222 (e.g., a dynamic micro-CT) in connectionwith positioning device 220. CT scanner 222 can identify the location oftarget T, as well as any peripheral structures of object O (e.g., normaltissue surrounding a tumor), and positioning device 220 can then be usedto align target T with a focus of microbeams MB.

In another aspect of the presently disclosed subject matter, a methodfor microbeam radiotherapy is provided. The method can comprisepositioning distributed x-ray source array 200 about target T to beirradiated (e.g., a tumor within a medical patient), x-ray source array200 comprising a plurality of carbon-nanotube field emission x-raysources 100, and simultaneously generating a plurality of x-raymicrobeams MB from the plurality of carbon-nanotube field emission x-raysources 100. X-ray source array 200 can be structured such that x-raymicrobeams MB can be generated from the plurality of field emissionx-ray sources 100 at different locations on x-ray source array 200.X-ray sources 100 can be switched to deliver x-ray microbeams MB toeither one or several parallel radiation planes on target T in a shorttime. A treatment planning program can be used to determine theradiation dose, the width of the x-ray beam, the spacing between thex-ray radiation planes, and the exposure time, each of which can becontrolled by a controller 220 in communication with x-ray source array200.

To generate multiple and parallel irradiation planes, either object O inwhich target T is contained or x-ray source array 200 can be translatedafter each exposure to a sequence of positions within a small interval,and x-ray source array 200 can be operated to irradiate target T aftereach translation. The process can be repeated until the entire area oftarget T is irradiated. In this way, x-ray source array 200 can deliverx-ray radiation to target T with the dose being distributed inalternating high and low dose planes.

The steps for an exemplary process according to this method are shown inFIG. 9. Specifically, a method for microbeam radiotherapy can compriseidentifying a region of interest (ROI) for irradiation (e.g., target T),and aligning the ROI with a radiation field. For instance, aligning theROI can comprise positioning object O on a patient bed and aligning theregion of interest of object O to be irradiated, such as a tumor (i.e.,target T), with a focus of x-ray microbeams MB. For example, apositioning device 220 discussed above can be used to align target Twith the radiation field. This alignment can be facilitated by firstlocating target T within object O. As discussed above, this locating canbe accomplished using an imaging device, such as an x-ray computedtomography scanner 222. It can be further advantageous to monitor thelocation of target T during the course of treatment. For example,physiological motions of object O generally or target T specifically canbe monitored, and the operation of x-ray source array 200 can besynchronized with such physiological motions, which can minimizeblurring of the irradiation field due to the motions. Once the ROI hasbeen aligned, the method can further comprise determining a dose, width,and spacing of the radiation plane generated by x-ray source array 200,and irradiating the ROI. As discussed above, either object O or x-raysource array 200 can be translated by a predetermined distance, and theirradiation process can be repeated until the entire ROI is irradiated.

In summary, compact systems and methods are disclosed that can generatespatially discrete x-ray microbeams with planar and other geometrieswith high dose rate for microbeam therapy. Such microbeam radiotherapysystems and methods can provide can be used for human cancer treatmentsuch as human external beam treatment, intra-operative radiationtherapy, brachytherapy, and for preclinical cancer research on animalcancer models.

The present subject matter can be embodied in other forms withoutdeparture from the spirit and essential characteristics thereof. Theembodiments described therefore are to be considered in all respects asillustrative and not restrictive. Although the present subject matterhas been described in terms of certain preferred embodiments, otherembodiments that are apparent to those of ordinary skill in the art arealso within the scope of the present subject matter.

What is claimed is:
 1. A method for image guided microbeam radiationtherapy, comprising: imaging a patient to identify a treatment region;positioning the patient in a microbeam irradiator, wherein theirradiator comprises a plurality of distributed x-ray source arrays,wherein each of the plurality of distributed x-ray source arrayscomprises one or more elongated focal tracks on a respective x-rayanode, and one or more of a microbeam collimator and a conformalcollimator; aligning the treatment region with a microbeam irradiatorposition; and irradiating the treatment region with a plurality ofmicrobeam arrays simultaneously from a plurality of entrance angles withprescribed beam energy, width, pitch, dose, andpeak-to-valley-dose-ratio.
 2. The method of claim 1, further comprisingsynchronizing or gating x-ray microbeam radiation delivery withphysiological motions to reduce motion induced microbeam dosimetryblurring.
 3. The method of claim 1, further comprising translating thepatient or the microbeam irradiator by a predetermined interval aftereach microbeam irradiation and repeating the process until an entiretreatment region is treated by the prescribed beam energy microbeamirradiation.
 4. The method of claim 1, wherein the plurality of thex-ray source arrays are configured to deliver an interfaced microbeamradiation pattern in the treatment region to increase valley dose forbetter tumor control while keeping the valley dose below a thresholdvalue for normal tissue sparing outside the treatment region.
 5. Acompact microbeam radiotherapy system comprising: a distributed x-raysource array positioned to surround an object to be irradiated andproduce x-ray radiation that directs towards a common treatment volume;a microbeam collimator positioned between the x-ray source array and theobject to be irradiated to collimate the x-ray radiation into either onemicrobeam or a plurality of substantially parallel microbeams; apositioning device for aligning a treatment target of the object withthe microbeams; and a control system in communication with the x-raysource array for generation of microbeams with pre-determined energy,x-ray dose and dose rate.
 6. The system of claim 5, wherein the x-raysource array comprises a field emission x-ray source array.
 7. Thesystem of claim 5, wherein a width of each microbeam is less than about1 millimeter and wherein separation between adjacent microbeams is lessthan 10 millimeters.
 8. The system of claim 5 wherein the x-ray sourcearray comprises multiple and parallel cathode arrays wherein the systemis configured such that an electron beam from each cathode array isfocused to a narrow line focusing track on an x-ray anode whereineffective width of each line focusing track is similar to a width of themicrobeam and effective spacing between the adjacent focusing track issimilar to spacing between adjacent microbeams.
 9. The system of claim 5further comprising an x-ray computed tomography imaging systempositioned for identifying location of the treatment target.
 10. Animage guided compact microbeam radiotherapy system comprising: amicrobeam irradiator comprising a distributed x-ray source arrayconfigured to produce x-ray radiation directed towards a commontreatment volume, a microbeam collimator to collimate the x-rayradiation into either one microbeam or a plurality of substantiallyparallel microbeams, and a conformal collimator configured to confinethe microbeam radiation to substantially only the treatment volume; animaging device for locating the treatment volume in an object; apositioning device for aligning the treatment volume with the microbeamor microbeams; a control system in communication with the x-ray sourcearray for generation of microbeams with pre-determined energy, x-raydose and treatment time; and an electronic control unit thatsynchronizes delivery of the x-ray radiation with physiological motionof the object to minimize motion induced microbeam beam width blurring.11. The system of claim 10 wherein the x-ray source array comprises anelectron field emission x-ray source array configured for synchronizingradiation delivery with physiological motion of the object by regulatingextraction voltage with physiological signals including cardiac andrespiratory signals of the object under treatment.
 12. An image guidedcompact microbeam radiotherapy system comprising: a microbeam irradiatorcomprising a plurality of distributed x-ray source arrays eachconfigured to produce a plurality of parallel and conformal microbeamsdirected toward a common treatment volume, wherein the microbeamsgenerated from each x-ray source array are substantially parallel toeach other and are interlaced at a treatment volume such that a highenergy density is deposited at the treatment volume compared to thesurrounding areas; an imaging device for locating the treatment volumein the object; a positioning device for aligning the treatment volumewith the microbeams; and a control system in communication with thex-ray source array for generation of microbeams with pre-determinedenergy, x-ray dose and treatment time.